Isaiah 9:2 (ESV) … “The people who walked in darkness have seen a great light; those who dwelt in a land of deep darkness, on them has light shone.”
The sign of coming light is Jesus. ‘Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.’ In Judah’s trouble, the virgin-born was God’s token that he would deliver and that speedily, for in less time than it would take such a child to reach years of knowledge, both of Judah’s royal adversaries would be gone.
The sign was good for Ahaz, but is far better for us. Behold the incarnate Son of God born of Mary at Bethlehem; what can this intend for us but grace? If the Lord had meant to destroy us, he would not have assumed our nature. If he had not been moved with mighty love to a guilty race, he would never have taken upon himself their flesh and blood. It is a miracle of miracles that the Infinite should become an infant, that he, who is pure spirit and fills all things, should be wrapped in swaddling bands and cradled in a manger. ‘He took not on him the nature of angels’, though that would have been a tremendous stoop from Deity, but he descended lower still, for ‘he took on him the seed of Abraham.’ He was made in all things ‘like unto his brethren,’ though he counted ‘it not robbery to be equal with God’.
It is not in the power of human lips to speak out all the comfort which this one sign contains. If any troubled soul will look believingly at God in human flesh, he must take heart of hope. If he looks believingly, his comfort will come speedily. The birth of Jesus is the proof of the good will of God to men: I am unable to conceive of proof more sure. He would not have come here to be born among men, to live among them, to suffer and to die for them, if he had been slow to pardon, or unwilling to save.